Production of high octane gasoline

Abstract

A moderate pressure hydrocracking process in which a highly aromatic, substantially dealkylated feedstock is processed directly to high octane gasoline by hydrocracking over a monofunctional acidic cracking catalyst, preferably comprising a large pore size, crystalline alumino-silicate zeolite hydrocracking catalyst such as zeolite Y. The feedstock which is preferably a light cycle oil obtained from catalytic cracking with an aromatic content of at least 50, usually at least 60 percent and an API gravity not more than 25. The hydrocracking typically operates at 600-1000 psig at moderate to high conversion levels to mazimize the production of monocyclic aromatics which provide the requiste octane value to the product gasoline.

We claim: 
     
       1. A process for producing a gasoline, which comprises hydrocracking a highly aromatic, substantially dealkylated hydrocarbon feed having an initial boiling point of at least 300° F., an end point up to about 750° F., an aromatic content of at least 50 weight percent, and a hydrogen content not more than 12.5 weight percent in the presence of hydrogen and a solid, porous monofunctional acidic cracking catalyst at a hydrogen partial pressure of not more than 1000 psig and a conversion of not more than 55 volume percent to gasoline boiling range products. 
     
     
       2. A process according to claim 1 in which the feed has an aromatic content of at least 60 weight percent. 
     
     
       3. A process according to claim 1 in which the feed has an aromatic content of at least 70 weight percent. 
     
     
       4. A process according to claim 1 in which the feed has a hydrogen content of 8.5 to 12.5 weight percent. 
     
     
       5. A process according to claim 1 inwhich the feed has an API gravity not more than 25. 
     
     
       6. A process according to claim 1 in which the feed has an API gravity not more than 20. 
     
     
       7. A process according to claim 1 in which the feed has an API gravity of 5 to 25. 
     
     
       8. A process according to claim 1 in which the hydrogen partial pressure is from 600 to 1000 psig. 
     
     
       9. A process according to claim 1 in which the conversion is not more than 0.05 times the hydrogen partial pressure expressed in psig. 
     
     
       10. A process according to claim 9 in which the feed has an end point in excess of 650° F. and up to about 750° F. 
     
     
       11. A process according to claim 9 in which the hydrocracking catalyst comprises a large pore size crystalline aluminosilicate zeolite. 
     
     
       12. A process according to claim 11 in which the zeolite comprises a zeolite having the structure of zeolite Y. 
     
     
       13. A process according to claim 11 in which the zeolite comprises zeolite Y, zeolite USY, or zeolite de-Aly. 
     
     
       14. A process according to claim 12 in which the zeolite has an alpha value up to 100. 
     
     
       15. A process according to claim 1 in which the hydrocracked, gasoline boiling range product has an octane rating of at least 87 (RON+0). 
     
     
       16. A process according to claim 1 in which the hydrocracked, gasoline boiling range product has an octane rating of at least 90. 
     
     
       17. A method according to claim 1 in which the feed is hydrotreated before being hydrocracked. 
     
     
       18. A method for the production of a high octane, hydrocracked gasoline, which comprises hydrocracking a highly aromatic light cut light cycle oil of the following properties:   ______________________________________                                    
API°      not more than 25                                         
Boiling range    300°-650° F.                               
Hydrogen content 8.5-12.5 wt. pct.                                        
Aromatic content at 1east 60 wt. pct.                                     
in the presence of hydrogen under the following conditions:               
Temperature      700°-850° F.                               
H.sub.2 partial pressure                                                  
                 600-100 psig                                             
385° F..sup.+  conversion                                          
                 Not more than 50 vol. pct.                               
______________________________________                                    
     in the presence of a hydrocracking catalyst comprising an monofunctional, aromatic-selective, large pore size crystalline, aluminosilicate zeolite having acidic functionality with an alpha value up to 100, to form a hydrocracked gasoline boiling range product having an octane number of at least 87 (RON+0).   
     
     
       19. A process according to claim 18 in which the zeolite is zeolite Y, zeolite USY or de-Aly. 
     
     
       20. A process according to claim 18 in which the conversion to gasoline boiling range products is 20 to 50 volume percent. 
     
     
       21. A process according to claim 18 in which the product gasoline has an octane number of at least 90 (RON+0). 
     
     
       22. A method for the production of a high octane, gasoline boiling range product which comprises hydrotreating a highly aromatic, dealkylated hydrocrabon feed having an initial boiling point of 300°-750° F., an aromatic content of at least 60 wt. pct., an API gravity of not more than 25, a hydrogen content of 8.5 to 12.5 wt. pct., contacting the hydrotreated feed in the presence of hydrogen with a monofunctional, acidic cracking catalyst comprising an aromatic-selective, large pore size crystalline aluminosilicate zeolite having cracking activity and an alpha value up to 100, at a hydrogen partial pressure of 600° to 850° F., a 385° F. +   conversion of not more than 50 vol. percent, to form a hydrocracked gasoline boiling range product having an octane number (RON+0) of at least 87. 
     
     
       23. A method according to claim 22 in which the hydrogen consumption is less than 1300 standard cubic feet per barrel (SCF/bbl) at a conversion (420° F. + ) of at least 20 vol. pct. 
     
     
       24. A method according to claim 23 in which the hydrogen consumption is less than 1200 standard cubic feet per barrel (SCF/bbl) at a conversion (420° F. + ) of 20 to 40 vol. pct.